only the 1st colour with AB (and Black/white primer), the rest with brush bud, its too small to get the transitions and over spray would be crazy, too much work masking if I did it that way. I blocked out the transition with 2BB stronger than a glaze, then smoothed it out with glazes of lots of lights and darks to get it looking good. Main advice is use your mid tone to cover all and soften the look then go over again and again until you feel its what you want.
For the lower areas its all wet blending off the colours on the base.